text: #include<stdio.h>
  int main()
  {
      int a,b,c;
      while(scanf("%d",&a)!=EOF){
          scanf("%d %d",&b,&c);
          if(a>b && b<=c)printf(":)\n");
          else if(a<b && b>=c)printf(":(\n");
          else if(a<b && b<c && (b-a)>(c-b))printf(":(\n");
          else if(a<b && b<c && (b-a)<=(c-b))printf(":)\n");
          else if(a>b && b>c && (a-b)>(b-c))printf(":)\n");
          else if(a>b && b>c && (a-b)<=(b-c))printf(":(\n");
          else if(a==b){
                  if(b<c)printf(":)\n");
                  else printf(":(\n");
          }
      }
      return 0;
  }
  